Geared hydraulic apparatus

ABSTRACT

Geared hydraulic apparatus comprising a sealing system for counter-balancing a side plate of the apparatus, which system is constituted by a single open gasket defining on the face of the side-plate adjacent a cover, two independent pressure regions respectively connected to the high and low pressure chambers defined by the toothed wheels in the recess of the body of the apparatus, the high pressure region being in the general shape of W skirting two bearings of the side-plate in order to terminate on the side opposite that corresponding to the central part of this high pressure region with respect to the plane of symmetry of the side-plate passing through the axes of the bearing of the latter.

[ 1 Sept. 30, 1975 3,473,476 10/1969 Davidson 418/132 3,482,524 12/1969Marietta 418/132 3539282 11/1970 Forschner.. 418/132 FOREIGN PATENTS ORAPPLICATIONS Primary Examiner-John J. Vrablik Attorney. Agent, orFirm-Alan H. Levine [57] ABSTRACT Geared hydraulic apparatus comprisinga sealing system for counter-balancing a side plate of the appara- .tus,which system is constituted by a single open gasket defining on the faceof the side-plate adjacent a cover. two independent pressure regionsrespectively connected to the high and low pressure chambers defined bythe toothed wheels in the recess of the body of the apparatus, the highpressure region being in the general shape of W skirting two bearings ofthe sideplate in order to terminate on the side opposite that Nogent surMarne,

. F01C 19/08; F03C 3/00;

F04C 15/O0;F01C

Field of Search........1............

Inventor: Roger Laumont,

France Assignee: Hydroperfect-International H P l Marne, France Filed:Jan. 23, 1974 Appl. No.: 435,926

Foreign Application Priority Data Jan. 23 1973 Int. Cl-" 418/102, 131

References Cited v UNITED STATES PATENTS United States Patent Laumont 1GEARED HYDRAULIC APPARATUS 2 Claims, 2 Drawing Figures corresponding tothe central part of this high pressure region with respect to the planeof symmetry of the side-plate passing through the axes of the bearing ofthe latter.

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4 e Ov/ wwwmww Mw www US, Patent Sept. 30.1975 3,909,165

II III GEARED HYDRAULIC APPARATUS The present invention relates togeared hydraulic apparatus intended to be used either as a pump or as amotor.

In the field of high performance geared hydraulic apparatus, apparatushas already been proposed which comprises two co-operating toothedwheels rotatable between two side-plates providing bearings and whichare disposed in a cylindrical recess provided in a central body anddefined by two opposed covers fixed to the latter in a fluid-tightmanner, the pressure on each side plate being substantiallycounter-balanced by a sealing system between the side-plate and theadjacent cover.

In previous such apparatus, the sealing system ensuring thecounter-balancing of pressure of each of the two side-plates in order tolimit to the maximum leakages which are able to occur between theopposing sides or the latter and the sides of the toothed wheels, isconstituted by a plurality of co-operating gaskets or portions ofgaskets disposed in appropriate grooves in the inner side of each coverin order to bear in a sealed manner partly against the adjacentside-plates and partly against the body. These gaskets or portions ofgaskets thus define on each side-plate, a number of independent pressureregions, overlapping each other in order to counter-balance on thisside-plate, the effects of hydraulic pressures occuring duringoperation, in the spaces of the two toothed wheels, over a wide range ofspeeds of rotation of the latter.

Such apparatus type provides complete satisfaction while making itpossible to obtain excellent mechanical and volumetric efficiency for anacceptable cost price considering the performance obtained.

Nevertheless, in certain relatively basic application, such asagricultural machines, for example, the more modest performances whichare required of the apparatus no longerjustify the relatively complexmachining of various grooves to be provided on the inner faces of thecovers.

The object of the present invention is to propose for such a gearedhydraulic apparatus a particularly simple and economical sealing systemproviding a good compromise for counter-balancing the hydraulic pressureon each of the side-plates for the range of customary speeds of rotationof the toothed wheels in order to make it possible to obtain acceptablevolumetric and mechanical efficiency.

With this aim in view, the geared hydraulic apparatus according to theinvention is characterized in that the sealing system is constituted bya single open gasket defining on the face of the side plate adjacent thecover, two independent pressure regions respectively connected to thehigh pressure and low pressure chambers defined by the wheels in therecess of the body, the high pressure region being in the general formof a W skirting the two bearings of the side-plate in order to terminateon the side opposite that corresponding to the central part of this highpressure region with respect to the plane of symmetry of the side-platepassing the axes of the bearings of the latter.

The W shape of the high pressure region makes it possible to obtainappropriate pressure counterbalancing of each side-plate in the field ofcurrent uses, either as a motor or as a pump, of the apparatus. Themounting of the open gasket may be effected simply by moulding it in onepiece with the side plate due to the simple shape of the gasket.

Preferably, each open gasket is disposed in a groove provided in theside of the corresponding side-plate which is adjacent the cover, thelength of the gasket being such that it ends abut against the walls ofthe cylindrical recess of the central body. With this particulararrangement, the ends of the gasket resulting from its assymetricalshape and its location between high and low pressure regions, tend to beurged into close contact with'the walls of the cylindrical recess of thebody thus eliminating the possibilities of leakages in the vicinity ofthese walls between said high and low pressure regions, at the ends ofthe gasket.

Advantageously, each side-plate comprises on its side adjacent thecover, two clearances capable, for the purpose of lubrication, ofconnecting the two bearings of the side-plate to the low pressurechamber of the recess and to the pressure region which is connectedthereto. This arrangement makes it possible to eliminate the internalpassages which are always difficult to machine and which it waspreviously necessary to provide in the covers with a view to connectingthe low pressure compensation regions, and possibly reservoirs for thelubricant for the bearings, to an appropriate external low pressuresource.

An embodiment of the present invention will now be described, by way ofexample with reference to the accompanying drawing, in which:

FIG. 1 is a sectional view of an apparatus according to the invention;

FIG. 2 is a view on line II- of FIG. 1.

In the drawings, the reference numeral 10 designates a geared hydraulicapparatus intended to be used either as a pump or as a motor. Theapparatus 10 comprises two co-operating toothed wheels 12 and 14respectively fixed to a driving shaft 16 and a driven shaft 18. The twoshafts 16 and 18 are supported to rotate on either side of the set ofwheels 12, and 14 by two sideplates forming a bearing 20 and 22 kept inabutting relationship, as explained hereafter, against the opposed sidefaces of the wheels 12 and 14.

The arrangement constituted by the wheels 12 and 14 and of theside-plates 20 and 22 is spectacle-shaped and is in a cylindrical recess24 of corresponding shape provided in the body 26. The latter comprisestwo radial passages 25 and 27 which open out respectively into a highpressure chamber 29 and a low pressure chamber 31 defined by the wheels12 and 14 in the recess 24 of the body 26 in the vicinity of the malepart of the spectacle-shaped arrangement on either side of the plane ofsymmetry of the apparatus passing through the axes of rotation of thetwo wheels 12 and 14. The recess 24 is closed at these ends by twocovers 28 and 30 appropriately retained on the opposed sides of the body26 by positioning pins 32 and screws 34. An annular gasket 33 housed ina closed groove provided in each cover 28 and 30 ensures the outer sealof the recess 24.

A hydraulic circuit for the circulation of low pressure fluid ofconventional type is provided for the lubrication of the bearings 36provided in the side plates 20 and 2 2 for the shafts. 16 and 18. Asshown, such a circuit consists of providing for each bearing 36, a setof four helical grooves 40 capable of connecting a recess 38 forming alubricant reservoir provided in the cover 28 or 30 corresponding to theside-plate 20 or 22 to a fluid-tight groove 42 and of providing betweenthe latter and the recess 38, a recycling conduit 44 in order to ensurea hydrodynamic circulation of the lubricant in the grooves 40 with adirection which depends on the direction of rotation of the toothedwheels 12 and 14.

It is known that in the abovedescribed apparatus, it is necessary tocompensate for the effect on each of the side-plates 20 and 22 of thehydraulic pressures occurring, during operation of the apparatus 10, inthe spaces between the teeth of the wheels 12 and 14 in order to keep toa minimum leakages which may occur between the sides of these wheels 12and 14 and the opposing sides of the side-plates 20 and 22 towards thegrooves 42.

This is done by providing a gasket means 46 between each of covers 28and 30 and the adjacent side-plate 20 and 22 in order to define on thelatter, independent regions kept at predetermined pressures, thearrangement of these regions and the value of these pressures being suchthat one achieves good counter-balancing of the various pressures actingon each of the side-plates, at least within the range of normalrotational speeds of the apparatus, or at approximately 15000 r.p.m. forexample.

Each gasket means 46, according to the invention, is constituted by anopen gasket 48, of round or rectangular section, housed in a groove 50provided in the face adjacent the cover of the corresponding side-plate.This gasket 48 thus defines on this face, a pressure region 52 which isconnected to a high pressure chamber 29 and a pressure region 54 whichis connected to the low pressure chamber 31. As shown in FIG. 2, thegroove 50 partly skirts the bearings 36 to open out in the outercylindrical wall of the side-plate at approximately 45 beyond the planeof symmetry of the latter passing through the axes of the two bearings36. With such a configuration of the groove 50 and of the gasket 48which is placed therein, the high pressure region 52 has the shape of aW skirting the two bearings 36 of the side-plate in order to terminateadjacent the aforesaid plane of symmetry which is opposite thatcorresponding to the central part of this region 52.

The low pressure region 54 which naturally has a complementary shape tothe region 52 from which it is separated by the gasket 48,advantageously comprises two clearances 56 capable of connecting therecesses 38 of the adjacent cover to the low pressure chamber 31 of theapparatus in order to keep the pressure in the lubrication circuits 38,40, 42, and 44, at a relatively low constant value.

When the apparatus is used as a pump, the aperture 27 forms the intakeaperture intended to be connected to a fluid reservoir (not shown)whereas the aperture 25 forms the delivery aperture intended to beconnected to a utilisation circuit (not shown), the driving shaft 16naturally rotating in counter-clockwise direction in the case of FIG. 2.

The high delivery pressure which thus occurs in the chamber 29 exerts anaction on the region 52 which substantially compensates for the actionon the sideplate envisaged of the pressures appearing in the spaces ofthe teeth of the wheels 12 and 14 within the range of normal speeds ofrotation.

It may be noted that the high pressure prevailing in the region 52tends, due to the extension of the ends of the gasket 48 beyond theplane of symmetry of the sideplate, to cause this gasket 48 to flowtowards its end; such a flow taking into account the arrangement of thisgasket in a groove provided in the side-plate and not in the cover canonly improve the contact between these ends and the opposing walls ofthe recess 24 and thus prevent a possible leakage between the regions 52and 54 in the vicinity. of the ends of the gasket 48.

When the apparatus 10 is used as a motor, the aperture 25 forms, incontrast to the case of use as a pump, the intake aperture intended tobe connected to a source of fluid pressure (not shown) whereas theaperture 27 forms the delivery aperture intended to be connected to atank (not shown). In this case, the rotation of the shaft 16 takes placein clockwise direction in the case of FIG. 2.

If it desired to retain the same direction of rotation of the apparatuswhen it is used as a motor as well as a pump, it is sufficient to rotatethe side-plates 20 and 22 by half a revolution in, order to connect theregion 52 to the chamber 31 and the region 54 to the chamber 29.

From the manufacturing point of view, it should be noted that thegrooves to be provided in the side-plates 20 and 22 and in the covers 28and 30 for housing the gaskets 33 and 48 as well as the recesses 38 andclearances 56 may be simply moulded in one piece with these parts which,as will be easily understood, simplifies the machining of the latter.

I claim:

1. A geared hydraulic apparatus comprising:

a body defining a central recess, covers secured to opposite ends ofsaid body to close the ends of said recess, said body having high andlowpressure fluid ports,

two spaced apart side plates within said recess, each side plate beingadjacent to one of said covers,

two cooperating toothed wheels within said recess and mounted on shaftsrotatably supported in bearings carried by said side plates,

a substantially W-shaped groove in the face of each side plate whichfaces its respective cover, each of said grooves partially skirting thebearings carried by its side plate and the ends of said grooveterminating at the edge of said side plate and normal to wall of saidrecess, the ends of said groove being arranged on opposite sides of saidlow pressure port and the top of the W opening toward said low pressureport, and the cross-sectional shape and dimensions of said groove indirections perpendicular to the length of said groove being constant,and

an elongated gasket in said groove, said gasket being of constantcross-sectional shape and dimensions in directions perpendicular to itslength, and said gasket being elongatable in response to fluid pressureat said high pressure fluid port so that the ends of said gasket arepressed against the wall of said recess to prevent fluid leakage aroundthe ends of said gasket.

2. A geared hydraulic apparatus as defined in claim 1 includingclearances formed in the face of each side plate which faces itsrespective cover, said clearances connecting the bearings carried bythat side plate to said low pressure fluid port.

1. A geared hydraulic apparatus comprising: a body defining a centralrecess, covers secured to opposite ends of said body to close the endsof said recess, said body having high and low pressure fluid ports, twospaced apart side plates within said recess, each side plate beingadjacent to one of said covers, two cooperating toothed wheels withinsaid recess and mounted on shafts rotatably supported in bearingscarried by said side plates, a substantially W-shaped groove in the faceof each side plate which faces its respective cover, each of saidgrooves partially skirting the bearings carried by its side plate andthe ends of said groove terminating at the edge of said side plate andnormal to wall of said recess, the ends of said groove being arranged onopposite sides of said low pressure port and the top of the W openingtoward said low pressure port, and the cross-sectional shape anddimensions of said groove in directions perpendicular to the length ofsaid groove being constant, and an elongated gasket in said groove, saidgasket being of constant cross-sectional shape and dimensions indirections perpendicular to its length, and said gasket beingelongatable in response to fluid pressure at said high pressure fluidport so that the ends of said gasket are pressed against the wall ofsaid recess to prevent fluid leakage around the ends of said gasket. 2.A geared hydraulic apparatus as defined in claim 1 including clearancesformed in the face of each side plate which faces its respective cover,said clearances connecting the bearings carried by that side plate tosaid low pressure fluid port.